FILE - This May 22, 2009 picture shows John Fenton, a farmer who lives near Pavillion in central Wyoming, near a tank used in natural gas extraction, in background. Fenton and some of his neighbors blame hydraulic fracturing, or "fracking," a common technique used in drilling new oil and gas wells, for fouling their well water. The U.S. Environmental Protection Agency announced Thursday Dec. 8, 2011 in Wyoming, for the first time that fracking may be to blame for causing groundwater pollution. The EPA also emphasized that the findings are specific to the Pavillion area. The agency said the fracking that occurred in Pavillion differed from fracking methods used elsewhere in regions with different geological characteristics.

FILE - This May 22, 2009 picture shows John Fenton, a farmer who lives near Pavillion in central Wyoming, near a tank used in natural gas extraction, in background. Fenton and some of his neighbors blame

FILE- In this Wednesday, April 15, 2009, file photo, an unidentified worker steps through the maze of hoses being used at a remote fracking site being run by Halliburton for natural-gas producer Williams in Rulison, Colo. The director of the Colorado Oil and Gas Conservation Commission, David Neslin, said Monday, Dec. 5, 2011, that requiring drilling companies to publicly disclose what chemicals they use in hydraulic fracturing is only one tool for protecting public health and the environment. The comment was made during a hearing regarding a proposal to require public disclosures of fracking fluids that aren't trade secrets. More than 100 people packed the hearing.

FILE- In this Wednesday, April 15, 2009, file photo, an unidentified worker steps through the maze of hoses being used at a remote fracking site being run by Halliburton for natural-gas producer Williams in

A federal report linking hydraulic fracturing with water contamination is providing fresh ammunition to opponents of the oil and gas production technology, but advocates showed no signs Friday of giving ground.

In a draft report released Thursday, the Environmental Protection Agency said its studies of a hydraulic fracturing site in Pavillion, Wyo., found hydraulic fracturing fluids and chemicals associated with gas production in deep water wells.

Hydraulic fracturing involves blasting a mix of water, sand and chemicals deep underground and at high pressures to break up dense shale rock and extract oil and natural gas.

The industry says the process is safe, but it's drawn strong opposition from environmentalists.

Separately, the EPA is writing new standards for how energy companies dispose of wastewater from natural gas drilling sites, and what they must do before injecting diesel into the ground as part of hydraulic fracturing operations.

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The new report “gives the EPA and the environmentalists a hook to hang on to,” said Dave Pursell, an analyst with the Houston-based investment bank Tudor, Pickering and Holt. “This really pushes this whole notion of best practice on well design.”

The new report is stoking calls for tighter controls — or outright bans — on fracturing in some areas.

And it provides fodder for an argument that the U.S. should adopt a nationwide standard for casing in wells that will be fractured, said Kevin Book, an analyst with ClearView Energy Partners in Washington.

Industry leaders long have argued that states — not the federal government — are in the best position to regulate hydraulic fracturing, because of vast differences in geology across the country.

For instance, while water can be recycled and reused in fracturing new wells in some parts of the country, the geology of other areas makes that impossible.

“State-level regulators themselves may seek to augment existing rules in an effort to stave off federal intervention,” Book said.

The Texas Railroad Commission, which regulates the state's oil field activities, dismissed the report's relevance to Texas, saying the circumstances were unique to the site in Wyoming.

Texas regulations prohibit fracturing that close to drinking water, the commission said in a response emailed to the Houston Chronicle.

“The Railroad Commission of Texas bases its regulatory decisions on science and fact,” it said in a statement emailed to the Houston Chronicle.

Railroad Commissioner David Porter, who heads up the agency's task force on operations in South Texas' Eagle Ford shale, called the EPA draft report “sensational headline seeking,” and said the geology of the Eagle Ford is vastly different from Wyoming's oil and gas fields.

Companies involved in hydraulic fracturing have been largely mum on the report.

Industry executives have insisted before that hydraulic fracturing is safe, contending that no cases of groundwater contamination had been directly linked to the practice.

Last month, Aubrey McClendon, CEO of Chesapeake Energy, a major natural gas producer, touted hydraulic fracturing as critical to the country's future at the Jefferies Global Energy Conference in Houston.

“If the nation wanted to commit economic suicide, it could ban fracking,” he told a roomful of analysts and industry players, using the oilfield slang for hydraulic fracturing.

A spokesman for Chesapeake said the company won't comment on the new report until it goes through peer review.

Preliminary findings released last month from a study by the University of Texas Energy Institute found no direct link between groundwater contamination and hydraulic fracturing in shale gas developments.

It did find water contamination associated with hydraulic fracturing of nonshale gas wells, said Ian Duncan, who's working on the UT study.

He said the EPA report and anecdotal reports of water contamination can't conclusively link the problem to hydraulic fracturing.

“There's all sorts of possibilities as to where these things come from,” he said, noting some fracturing chemicals including benzene and 2-butoxy ethanol also are in gasoline and household cleaners.

“There's some possibility that these chemicals are just coming from people inappropriately disposing of chemicals. I'm a little suspicious of it. It's not what I would call a smoking gun.”